While it's true that a square wave is going to produce an audible (honk)
before a sine wave, you have to keep in mind that anyone running 60+wpm is
not going to be too concerned about a delay since he would no doubt be
keying several characters ahead of the sidetone anyway.
One easy trick that will clean up a square wave sidetone is to use an audio
filter on the output of the rig. Any simple filter, active or passive, will
work fine. I've used the popular Autek QF-1 which is available on the used
market for about $30 and it does wonders for square waves but it does tend
to enhance the agc overshoot pop problem in old TT rigs.
I have a MFJ DSP filter with it's own built in AGC and that cures both
problems. For the money, I think it's hard to beat the MFJ 784B filter and I
believe TT even sells these. Another nice feature about the MFJ is that it
doesn't induce much delay so you don't need to worry about bypassing it when
transmitting like you do with certain other brands.
It's interesting that the Delta 580 has a beautiful sinewave sidetone.
Correct me if I'm wrong but didn't it come out before the Corsair II?
Steve
N4LQ
----- Original Message -----
From: "Mike Hyder -N4NT-" <N4NT@charter.net>
To: <tentec@contesting.com>
Sent: Friday, February 07, 2003 11:41 PM
Subject: Re: [TenTec] playing with the Corsair II
> If memory serves, Steve's mod to the Corsair II sidetone has one drawback:
> it is a slower starting oscillator and therefore might not be very good
for
> QRQ.
>
> 73, Mike N4NT
>
> ----- Original Message -----
> From: "Chester" <calderman@cox.net>
> To: <tentec@contesting.com>
> Sent: Friday, February 07, 2003 5:17 PM
> Subject: RE: [TenTec] playing with the Corsair II
>
>
> > Hi Irv,
> >
> > Good to hear from ya.
> >
> > Irv, there is two things you can do to that sidetone (square
> > wave) generator in the CII. Since I had a spare Ten Tec audio filter
> > from an old Triton xcvr (think it's a model 285), I just removed R90
> > (47k) between the center arm of the S.T. LEVEL pot and the input to U5,
> > the audio amp (in my schematic). I ran a wire from the resistor hole
> > from the pot arm to the input of the filter and from the output of the
> > filter, I ran a second wire to the resistor hole going to the input of
> > the audio amp.
> >
> > I then 'jury-rigged' a mechanical means of physically mounting
> > the audio filter board just about the CII's IF board and I connected +12
> > and ground between the filter board and the IF board. (Of course you
> > could use any audio filter you have available to run that square wave
> > through to drastically improve the sidetone.) The old Triton board was
> > good enough because if I recall correct, it had three audio bandwidth's
> > to select from.
> >
> > The second mod you could try, and it's a much more professional
> > approach, is a circuit that Steve, N4LQ came up with to replace the
> > entire square wave sidetone generator. It's not complicated and you can
> > see his schematic at:
> >
> > http://www.albany.net/~bg/Mods/sidetone.htm
> >
> > I also just acquired another Corsair II (think this is about my
> > sixth CII!!), so I'm soon going to have to make the mod again if I
> > decide to keep this CII. Let me know which mod you make Irv.
> >
> > 73,
> >
> > Tom/W4BQF
> >
> > Chester Alderman
> > calderman@cox.net
> >
> > -----Original Message-----
> > From: tentec-bounces@contesting.com
> > [mailto:tentec-bounces@contesting.com] On Behalf Of Irvin Weinman
> > Sent: Friday, February 07, 2003 10:57 AM
> > To: tentec@contesting.com
> > Subject: Re: [TenTec] playing with the Corsair II
> >
> > Tom: I am acquiring another Corsair II. I remember years ago you had
> > given
> > out the tech data to CFO types, for an audio filter mod to tame the
> > annoying
> > sidetone. Do you still have that information around? Irv W7GX.
>
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